As the scan of two pages from a book on the Jewish Qabalah attests,
the exact same black and white hexagram that's used in
Freemasonry is also used by Kabbalists and has the same
meaning. The scan above is from Gonzalez Whippler's
book "Kabbalah for the Modern World",
where she describes the same symbol in the same way as
it's described in Freemasonry; that is, the downward triangle represents
water, the upward triangle represents fire, i.e., the
triangles represent opposite principles in nature.
According to the Lexicon of Freemasonry, the "Talmudists
say that it was inscribed on the foundation
stone of the Temple." (Lexicon of Freemasonry, page
432, Albert Mackey, 33rd Degree Freemason)
This would also seem to suggest the significance of the Seal of
Solomon in Judaism.